Fluorinated COFs for Hydrogen Storage Without Pore Collapse
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Solution Overview
Problem
Current hydrogen storage materials face challenges such as low hydrogen storage capacity, high cost, and instability due to high specific surface area and pore collapse, with existing methods failing to meet the density requirements set by the United States Department of Energy and requiring complex and costly modifications.
Innovation Solution
A method involving fluorination treatment of a specific site on the aromatic ring of a covalent organic framework (COF) compound is used to increase hydrogen adsorption heat and storage capacity, employing dehydration and polycondensation of aromatic polyamino and polyaldehyde monomers with fluorinated aromatic rings to form two- or three-dimensional structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the specific surface area of COF material is increased to improve hydrogen storage capacity, then the hydrogen storage capacity is improved, but the material stability deteriorates due to pore collapse
Solution Approach 1:
The patent applies local quality by introducing fluorine atoms at specific positions on the aromatic rings of COF monomers. This local chemical modification changes the electron distribution and adsorption properties of specific regions without altering the overall framework structure, thereby improving hydrogen storage capacity while maintaining material stability.
Solution Approach 2:
The patent changes chemical parameters by substituting hydrogen atoms with fluorine atoms on the aromatic rings. This parameter change (fluorination) modifies the electronic properties and adsorption heat of the COF material, enabling improved hydrogen storage performance without requiring increased specific surface area that would compromise structural stability.
2Quantity of substance
If complex modification methods are used to improve hydrogen storage performance, then the hydrogen storage capacity is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by incorporating fluorine atoms directly into the monomer structures before COF assembly. This pre-fluorination allows the desired chemical modification to be achieved during the standard COF synthesis process, eliminating the need for subsequent complex post-synthesis modification steps and reducing manufacturing complexity.
Solution Approach 2:
By changing the chemical composition parameter (introducing fluorine) at the monomer level, the patent achieves improved hydrogen storage performance through a straightforward synthesis approach rather than complex multi-step modifications, thereby reducing manufacturing complexity and cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly enhances hydrogen storage capacity and adsorption performance without increasing specific surface area, offering a simple and cost-effective solution applicable at an industrial scale, suitable for both two- and three-dimensional COF compounds.
Implementation Method 1
The physisorption hydrogen storage is a process of accumulating gas molecules on the surface of a material without undergoing chemical reactions with the material by virtue of the intermolecular interactions between the gas and the material to adsorb and store the gas.
Implementation Method 2
Adsorption is a phenomenon of partial retention of gas and solid after contact, and may be divided into two categories: chemisorption and physisorption according to the difference in adsorption force, adsorption heat, adsorption rate, selectivity, adsorption temperature, pressure and the like.
Implementation Method 3
The physisorption hydrogen storage is a process of accumulating gas molecules on the surface of a material without undergoing chemical reactions with the material by virtue of the intermolecular interactions between the gas and the material to adsorb and store the gas.
Data Source
AI summary
The disclosure provides a method for improving hydrogen storage performance of a covalent organic framework compound, including: enabling an aromatic polyamino monomer and an aromatic polyaldehyde monomer to be subjected to dehydration and polycondensation to form the covalent organic framework compound, where the aromatic polyamino monomer and/or the aromatic polyaldehyde monomer contains at least one fluorinated aromatic ring, at least one hydrogen atom on the fluorinated aromatic ring is substituted with fluorine, hydrogen atoms not substituted with fluorine exist on the fluorinated aromatic ring, and the covalent organic framework compound has a two-dimensional or three-dimensional structure.